Adjustable chair

ABSTRACT

The present invention relates to an adjustable chair ( 10 ) comprising: a seat base ( 12 ) defining a seating surface portion ( 14 ) for receiving a user thereon in use, the seat base ( 12 ) comprising an integral seat back engagement portion ( 20 ) for engaging with a portion of a seat back ( 16 ), a seat front portion ( 40 ) opposing the seat back engagement portion ( 20 ), a first seat side portion and a second seat side portion opposing the first seat side portion, each of the first and second seat side portions located between the seat back engagement portion ( 20 ) and the seat front portion ( 40 ) and extending substantially transverse to the seat surface portion ( 14 ); and a seat back ( 16 ) having a seat base engagement portion ( 18 ) dimensioned to slidably engage with the seat back engagement portion ( 20 ) to form a seat back adjustment mechanism, wherein the seat back adjustment mechanism is located adjacent at least one of the first and second seat side portions and wherein the seat back adjustment mechanism is movable between a first locked configuration in which the seat back ( 16 ) and seat base ( 12 ) are fixed relative to one another and the seating surface portion ( 14 ) has a fixed surface area, and a second released configuration in which the seat back ( 16 ) is slidable relative to the seat base ( 12 ) to vary the surface area of the seating surface portion ( 14 ). Also provided is such a chair with an adjustable footrest ( 22 ) to vary the distance between the seat base ( 12 ) and the footplate ( 54 ) and/or to vary the angle between the seat base ( 12 ) and the footrest ( 22 ).

BACKGROUND OF THE INVENTION

Conventional chairs are designed to fit and support a user's body. Someare adjustable with respect to arm rest height or the incline of theback support. Some include adjustable lumbar supports for optimalsupport of the user's spine.

However, these adjustability options are not sufficient for a chair foruse by users of multiple heights and body shapes. For example, a schoolchair may be used by a schoolchild over many months, during which timethe schoolchild will be growing in height and weight. Gradually, theywill outgrow the chair which leads to discomfort, poor posture andpotentially back pain. Alternatively, a school chair may be used by morethan one child of differing heights and body shapes on a regular basis.However, without sufficient adjustability the chair will not be suitablefor all.

As children grow, their leg length increases. Thus, an increase in theirlower leg length will require a chair of increasing height to ensurethat the child's foot can be flat on the floor whilst the underside oftheir leg makes contact across the seat base. This means that some ofthe load is supported through the feet whilst the underside of the leghas even pressure against the seat base. This seated position tends toresult in an approximate 90° bend at the knee when the child is properlyseated and supported by the chair. Further, an increase in their upperleg length will require a chair with a deeper seat base to ensure thattheir upper leg is sufficiently supported in a direction towards theknee. To keep measuring children throughout their time at school andprovide a new chair of suitable dimensions to accommodate their growthon a regular basis is time-consuming and expensive.

There is therefore a need for a chair that is suitably adjustable toaccommodate the changing leg length of the child over time.

SUMMARY OF THE INVENTION

The present invention seeks to address the problems of the prior art.Aspects of the present invention are set out in the attached claims.

According to a first aspect of the present invention, there is providedan adjustable chair comprising: a seat base defining a seating surfaceportion for receiving a user thereon in use, the seat base comprising anintegral seat back engagement portion for engaging with a portion of aseat back, a seat front portion opposing the seat back engagementportion, a first seat side portion and a second seat side portionopposing the first seat side portion, each of the first and second seatside portions located between the seat back engagement portion and theseat front portion and extending substantially transverse to the seatsurface portion; and a seat back having a seat base engagement portiondimensioned to slidably engage with the seat back engagement portion toform a seat back adjustment mechanism, wherein the seat back adjustmentmechanism is located adjacent at least one of the first and second seatside portions and wherein the seat back adjustment mechanism is movablebetween a first locked configuration in which the seat back and seatbase are fixed relative to one another and the seating surface portionhas a fixed surface area, and a second released configuration in whichthe seat back is slidable relative to the seat base to vary the surfacearea of the seating surface portion.

Thus, the depth of the seat base can be varied by moving the seat backrelative to the seat base to adjust the seating area available for auser to sit on, in use. Thus, for a user of lesser height, the seatingsurface portion and thus seat depth can be adjusted to bring the seatback closer to the front of the seat base to allow the user to sitcomfortably with their back against the seat back.

Having the seat back engagement portion integral with the seat baseprovides the advantage of simplification of design, with associated costsavings, and increased ease of assembly. Further, the integral nature ofthe seat back engagement portion and seat base provide the chair withgreater structural integrity and strength.

The location of the seat back adjustment mechanism is important. Theseat back adjustment mechanism is provided on the outside edge of theseat base i.e. adjacent at least one of the first and second seat sideportions, rather than underneath the seat base. This increases thevisibility of the seat back adjustment mechanism.

Further, the seat back adjustment mechanism is provided on the outsideedge of the seat base, rather than on the upper surface of the edge ofthe seat base, to avoid the adjustment mechanism collecting dust andpotentially having objects inserted in it e.g. chewing gum and the like,which could potentially damage the mechanism. Further, if provided onthe upper surface of the edge of the seat base, a user sitting on thechair could inadvertently apply downward force on the mechanism, therebyreleasing the latch from the recess and accidentally allowing the seatback to slide relative to the seat base.

In one embodiment, the seat back adjustment mechanism comprises: a firstengagement portion for engagement with a latch; and a latch pivotableabout a pivot point, the latch comprising a second engagement portionfor engagement with the first engagement portion, wherein the latch ispivotable between the first locked configuration in which the first andsecond engagement portions are in rigid engagement with one another andthe seat back and seat base are fixed relative to one another, and thesecond released configuration in which the first and second engagementportions are in slidable engagement with one another and the seat backis slidable relative to the seat base.

In one embodiment, the first engagement portion comprises a plurality ofrecesses, each recess being dimensioned to receive at least a portion ofthe second engagement portion therein.

Preferably, the latch is biased towards the first engagement portion.

The latch may be biased towards the first engagement portion under forcefrom a coil spring engaged with the latch and arranged between the latchpivot point and the second engagement portion.

Preferably, the latch is pivotable between the first lockedconfiguration and the second released configuration on application offorce to a portion of the latch located distal to the second engagementportion.

In one embodiment, the seat base engagement portion comprises the firstengagement portion and the seat back engagement portion comprises thelatch.

Preferably, the seat back is provided as a single-piece moulding. Thisprovides strength to the chair and stability for the slidable movementof the back rest relative to the seat base.

More preferably, the seat back is provided with a plurality of apertureswhich act as air-holes to provide ventilation to the back of a user whensitting in the chair. The apertures further allow controlled flexing ofthe seat back by a user when sitting in the chair, thus increasing thecomfort of a user, during use.

In one embodiment, the adjustable chair comprises a second seat backadjustment mechanism such that a seat back adjustment mechanism islocated adjacent each of the first and second seat side portions, bothseat back adjustment mechanisms must be moved from the first lockedconfiguration to the second released configuration to allow the seatback to be slidable relative to the seat base.

In a further embodiment, the adjustable chair further comprises afootrest extending away from the seat base, the footrest comprising: afirst footrest portion extending away from the seat base, the firstfootrest portion comprising a footrest engagement portion for engagementwith a second footrest portion; and a second footrest portion comprisinga footplate for receiving the feet of a user in use, the second footrestportion having a first footrest engagement portion dimensioned toslidably engage with the footrest engagement portion to form a footrestadjustment mechanism, and the footplate being arranged distal to thefirst footrest engagement portion, wherein the footrest adjustmentmechanism is moveable between a footrest locked configuration in whichthe first and second footrest portions are in fixed engagement with oneanother and the footplate is at a fixed distance from the seat base, anda footrest released configuration in which the first and second footrestportions are slidable relative to one another to adjust the distancebetween the footplate and the seat base.

In one embodiment, the footrest adjustment mechanism comprises: a firstengagement portion for engagement with a latch; and a latch pivotableabove a fixed pivot point, the latch comprising a second engagementportion for engagement with the first engagement portion, wherein thelatch is pivotable between the footrest locked configuration and thefootrest released configuration.

In one embodiment, the footrest adjustment mechanism first engagementportion comprises a plurality of recesses, each recess being dimensionedto receive at least a portion of the footrest adjustment mechanismsecond engagement portion.

Preferably, the footrest adjustment mechanism latch is biased towardsthe plurality of recesses of the footrest adjustment mechanism.

The footrest adjustment mechanism latch may be biased towards theplurality of recesses of the footrest adjustment mechanism under forcefrom a second coil spring engaged with said latch and arranged betweenthe pivot point of said latch and the footrest adjustment mechanismlatch recess engagement portion.

Preferably, the footrest adjustment mechanism latch is pivotable betweenthe footrest locked configuration and the footrest releasedconfiguration on application of force to a portion of the said latchlocated distal to the latch recess engagement portion.

In one embodiment, the first footrest portion comprises the firstengagement portion and the second footrest portion comprise the footrestadjustment mechanism latch.

In one embodiment, the first footrest portion is pivotally engaged withthe seat base.

Preferably, the footrest is pivotable from the vertical position to aposition beneath the seat base. This allows the user to move thefootrest backwards slightly when standing in position to lowerthemselves into the chair. As the user's feet move slightly beneath theseat base in the normal manner, the footrest will be swung away from thevertical in a direction towards the seat base by the lower legs of theuser as their feet are moved under the chair. This movement of thefootrest is particularly beneficial when a user slides the chairforwards, for example, when sliding the chair under a desk. The user'sfeet will inevitably end up beneath the chair as they are sliding it,and the benefit of the footrest swinging away from the vertical isextremely beneficial in such a situation.

In one embodiment, the footrest is pivotable from the vertical positionin a direction away from the seat base.

An adjustable chair as claimed in claim 15, wherein the seat basedefines a first plane and the footrest pivots in a second plane, whereinthe first and second planes are transverse to one another.

The footrest pivot position is carefully selected so that it is atapproximately the same height as the natural pivot point of the user'sknee joint. Thus, when swinging, the footplate remains at approximatelythe same distance from the knee of the user. This also allows anincreased level of upward swing movement of the footrest.

A further advantage of a swinging footrest is the ability of a user e.g.a child, to move the footrest (in a fidgeting fashion) while restingtheir feet on it during use of the chair. Studies have demonstrated thatthis leg movement in children can assist with concentration duringlearning events and assists with the dissipation of excess energy,whilst remaining in the seated position.

A further advantage of the footrest feature is safety related. Whilstusing a chair with a footrest that is adjustable to accommodate theleg-length of the user, the user is less likely to attempt to put theirfeet on the floor during use of the chair and try to push backwards suchthat the chair tips on the rear legs. Excess tipping can destabilise thechair, resulting in the child being injured as they fall backwards withthe chair.

A further advantage of the chair of the present invention is that theheight of the chair is fixed, and it is the backrest and/or footrestthat are adjustable in dependence upon the dimensions of the user. Thus,in a classroom setting, every child will be sitting at the same heighton the base. Thus, no matter the height of an individual child, theywill be at the same level as their peers of various different heights tothemselves. Further, this means that each child will be seated at anappropriate height to use fixed height desks and tables.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a view from one side of an embodiment of a chair in accordancewith the present invention;

FIG. 2 is a front view of the chair of FIG. 1;

FIG. 3 is a view from the other side of the chair of FIG. 1;

FIG. 4 is a rear view of the chair of FIG. 11;

FIG. 5 is a perspective view from behind of the chair of FIG. 1;

FIG. 6 is a perspective view from the front of the chair of FIG. 1;

FIG. 7 is a view from above of the chair of FIG. 1;

FIG. 8 is a view from below of the chair of FIG. 1;

FIG. 9 is a front view of the chair back of the chair of FIG. 1;

FIG. 10 is a perspective view of the chair back of FIG. 9;

FIG. 11 is a front view of the footrest of the chair of FIG. 1 in anextended configuration;

FIG. 12 is a perspective view of the footrest of FIG. 11;

FIG. 13 is a front view of the footrest of the chair of FIG. 1 in aretracted configuration;

FIG. 14 is a perspective view of the footrest of FIG. 13;

FIG. 15 is a perspective view of the chair of FIG. 1, showing the footrest in an extended configuration and the back rest in an extendedconfiguration;

FIG. 16 is a perspective view of the chair of FIG. 1, showing thefootrest in a retracted configuration and the chair back in a retractedconfiguration;

FIG. 17 is a side view of the chair of FIG. 15;

FIG. 18 is a side view of the chair of FIG. 16:

FIG. 19 is a front view of the chair of FIG. 15;

FIG. 20 is a front view of the chair of FIG. 16;

FIG. 21 is a side view of the chair of FIG. 1, showing the footrest inan extended configuration and pivoted outwards from the chair base;

FIG. 22 is a side of the chair of FIG. 1, showing the footrest in anextended configuration and pivoted inwards under the chair base;

FIG. 23 is a perspective view of the chair of FIG. 22;

FIG. 24 is a perspective view of the chair of FIG. 23;

FIG. 25 is a block illustration of the front view of the chair of FIG.1;

FIG. 26 is a section B-B through the chair of FIG. 25;

FIG. 27 is a section A-A through the chair of FIG. 25;

FIG. 28 is an enlarged view of the detail D of FIG. 26;

FIG. 29 is an enlarged view of the detail C of FIG. 27;

FIG. 30 is a side view of a user sitting in an embodiment of a chair inaccordance with the present invention with the footrest swung forward(the adjustable backrest is not shown); and

FIG. 31 is a side view of the user and chair of FIG. 30 with thefootrest swung under the seat base.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Throughout the figures, the same figures references have been used torefer to the same features of the invention.

The figures show an adjustable chair 10 comprising a seat base 12adapted to receive a user thereon in use and defining an exposed seatingsurface area 14 for receiving a user thereon in use. Seat base 12 issubstantially planar. Although shown as a one-piece moulding, it will beappreciated that the seating surface area 14 may padded for the comfortof the user. In the embodiment shown, the front edge 40 of seat base 12is shown as curved, in a contour known in the industry as a ‘waterfall’front edge. This assists with the comfort of a user and the back of auser's knees are supported by a smooth curved surface.

The chair 10 further comprises a seat back 16. Seat back 16 has anelongate U-shaped seat base engagement portion 18 and seat base 12 has acorresponding seat back engagement portion 20 which is an elongatetubular structure and is dimensioned to fit within the U-shaped seatbase engagement portion and is in slidable engagement with seat backengagement portion 20 to form an adjustment mechanism 24.

Seat back adjustment mechanism 24 is composed of the seat baseengagement portion 18 and the seat back engagement portion 20.

Seat back engagement portion 20 is provided with a plurality of recesses26 and seat base engagement portion 18 is provided with a latchmechanism.

The latch mechanism comprises a latch 28 which is pivotably about fixedpivot point 30 and a coil spring 32. Latch 28 comprises a coil springengagement portion 34 which is engaged with coil spring 32. Latch 28further comprises a recess engagement portion 36 located on the sameside of the pivot point 30 as the coil spring 32. Recess engagementportion 36 is located adjacent recesses 26 and is dimensioned to bereceived within one of the plurality of recesses. Coil spring 32 biasesthe latch 28 towards the recesses 26 and holds the latch recessengagement portion 36 within a selected recess 26, in use.

The button portion 38 of latch 28 distal to the recess engagementportion 36 comprises a convex surface to allow easy engagement by a userduring adjustment of the seat back adjustment mechanism.

Latch 28 is provided such that the button portion 38 is presented on theoutward edge of the seat base 12. This allows ease of access for a user,whilst avoiding the disadvantages of conventional chairs whereadjustment mechanisms are provided on the upper surface of the edge ofthe seat base i.e. foiling of the adjustment mechanism by dust and otherdebris. Further, the potential danger of accidental release of theadjustment mechanism by inadvertently leaning on it, is avoided.

Thus, in use, the recess engagement portion 36 of latch 28 is biased bycoil spring 32 into a recess 26, thus preventing the seat baseengagement portion 18 and seat back engagement portion 20 from beingslidable relative to one another. It is to be appreciated that, when thebackrest is pushed backwards, once engaged, any pressure applied to thelatch mechanism (apart from pressure applied to button portion 38) willnot encourage the latch 28 to be released from the recess 26. Instead,the recess engagement portion 36 will be more firmly pushed intoengagement with the recess 26.

On application of force by a user to the button portion 38 of latch 28,latch 28 is pivoted about the fixed pivot point 30 to compress coilspring 32 and move coil spring engagement portion 36 of latch 28 out ofengagement with recess 26. Once the coil spring engagement portion 36and recess 26 are disengaged, seat base engagement portion 18 and seatback engagement portion 20 can be slidably moved relative to one anotherthus moving the seat back relative to the seat base and altering theexposed seating surface are 14.

Seat base 12 has a front edge 40 and a rear edge 42. Movement of theseat back 16 in a direction from the rear edge 42 of seat base 12towards the front edge 40 of seat base 12 will reduce the exposed seatsurface area 14. Subsequent return movement of the seat back 16 towardthe rear edge 42 of seat base 12 will increase the exposed seatingsurface area 14 available for a user to sit on.

After slidable movement of seat back 16 relative to seat base 12,release of force on button portion 38 of latch 28 will allow the latch28 to pivot back about fixed pivot point 30 under the biasing influenceof coil spring 32 as it decompresses, thus bringing recess engagementportion 36 of latch 28 back into contact with the seat back engagementportion so that the recess engagement portion 36 of latch 28 may onceagain engage with one of the recesses 26. The amount of adjustment madeto the seating surface area 14 depends on the amount of movement of seatbase engagement portion 18 relative to seat back engagement portion. Theplurality of recesses is provided at staggered intervals to permit aplurality of points of adjustment and therefore a corresponding numberof different sizes of seating surface area 14 that may be achieved usingthe same adjustable chair. Typically, the range of adjustment will besufficient to accommodate the anticipated range of heights of potentialusers of the chair. Ideally, the plurality of recesses will be evenlyspaced and sufficient in number to cover the full range of adjustmentand allow incremental adjustments to be made to suit the requirements ofa user.

Thus, adjustment of the position of the seat back 16 relative to theseat base 12 will vary the seating surface area 14 and, in particular,will vary the distance between the seat back 16 and the front edge 40 ofseat base 12. This allows the same adjustable chair to be used by usersof different heights. More specifically, the chair can be adjusted tosuit users where the distance between the hips and knees of each uservaries. This is particularly important where the chair is to be used byan individual child who will grow in height over time or where the chairis to be used by multiple individuals of different heights and/or femurlengths.

Seat back 16 is provided as a single-piece moulding and is provided withapertures 17. The single-piece moulding provided stability to the seatback adjustment mechanism, whilst apertures 17 act as ventilation toallow air to circulate around the back of the user to increase comfortlevels during use. Further, apertures 17 allow a controlled level offlex within the seat back 16, thus further assisting with the comfort ofthe user when sitting in the chair 10.The chair 10 is further providedwith a footrest 22 extending from the front edge 40 of seat base 12. Thefootrest is specifically shown in FIGS. 11 and 12 and comprises a firstfootrest portion 44 and a second footrest portion 46 engaged with firstfootrest portion 44. First footrest portion 44 extends away from theseat base 12 and comprises a second footrest engagement portion 48 forengagement with the second footrest portion 46. First footrest portion44 further comprises a seat base attachment portion 50 which engageswith footrest attachment portion 52 of seat base 12.

Second footrest portion 46 comprises a footplate 54 for receiving thefoot of a user in use. The footplate 54 is arranged distal to the firstfootrest portion 44. Second footrest portion 46 further comprises afirst footrest engagement portion 56 dimensioned to slidably engage withthe second footrest engagement portion 56 on the first footrest portion44. First and second footrest engagement portions form a footrestadjustment mechanism 58.

Footrest adjustment mechanism 58 is composed of the second footrestengagement portion 50 of the first footrest portion 44 and the firstfootrest engagement portion 56 of the second footrest portion 46.

First footrest portion 44 is provided with a plurality of recesses 64and second footrest portion 46 is provided with a latch mechanism.

The latch mechanism comprises a latch 60 which is pivotable about fixedpivot point 62 and a coil spring 70. Latch 60 comprises a coil springengagement portion 72 which is engaged with coil spring 70. Latch 60further comprises a recess engagement portion 74 located on the sameside of the pivot point 62 as the coil spring 70. Recess engagementportion 74 is located adjacent recesses 64 and is dimensioned to bereceived within one of the plurality of recesses 64. Coil spring 70biases the latch 60 towards the recesses 64 and holds the latch recessengagement portion 74 within a selected recess 64, in use.

The button portion 76 of latch 60 distal to the recess engagementportion 74 comprises a convex surface to allow easy engagement by a userduring adjustment of the footrest adjustment mechanism 58.

Thus, in use, the recess engagement portion 75 of latch 60 is biased bycoil spring 70 into a recess 64, thus preventing the first footrestengagement portion 56 and the second footrest engagement portion 48 frombeing slidable relative to one another. Once engaged, any pressureapplied to the footrest in a downward direction will not encourage thelatch 60 to be released from the recess 64. Instead, the recessengagement portion 75 will be more firmly pushed into engagement withthe recess 64 on application of downward pressure on the footplate 54 bythe feet of a user.

On application of force by a user to the button portion 76 of latch 60,latch 60 is pivoted about the fixed pivot point 62 to compress coilspring 70 and move coils spring engagement portion 72 of latch 60 out ofengagement with recess 64. Once the coil spring engagement portion 72and recess 64 are disengaged, the first footrest engagement portion 56may be slidably moved relative to the second footrest engagement portion48, thus moving the second footrest portion 46 relative to the firstfootrest portion 44 and altering the distance between the footplate 54and the front edge 40 of seat base 12.

Movement of the second footrest portion 46 in a direction away from theseat base 12 will extend the length of the footrest 22, thus extendingthe distance between the footplate 54 and the seat base 12. Subsequentreturn movement of the second footrest portion 46 back towards the seatbase 12 will reduce the length of the footrest 22 and thus bring thefootplate 54 closer to the seat base 12.

After slidable movement of the second footrest portion 46 relative tothe first footrest portion 44, release of force on button portion 74 oflatch 60 will allow the latch 60 to pivot back about fixed pivot point62 under the biasing influence of coil spring 70 as it decompresses,thus bringing recess engagement portion 74 of latch 60 back into contactwith the second footrest engagement portion 48 so that the recessengagement portion 74 of latch 60 may once again engage with one of therecesses 64. The amount of adjustment made to the length of the footrest22 depends on the amount of movement of the first footrest engagementportion 56 relative to the second footrest engagement portion 48. Theplurality of recesses 64 are provided at staggered intervals to permit aplurality of point of adjustment and therefore a corresponding number ofdifferent footrest 22 lengths that may be achieved using the sameadjustable chair.

Thus, adjustment of the position of the second footrest portion 46relative to the first footrest portion 44 will vary the overall lengthof the footrest 22 and, in particular, will vary the distance betweenthe footplate 54 and the front edge 40 of seat base 12. This allows thesame adjustable chair to be used by users of different heights. Morespecifically, the footrest can be adjusted to suit users where thedistance between the feet and knees of each user varies. This isparticularly important where the chair is to be used by an individualchild who will grow in height over time or where the chair is to be usedby multiple individuals of different heights and/or tibia lengths.

Thus, without the need to alter the height of the chair, a user who isnot sufficiently tall to place their feet on the ground when sitting inthe chair can still use the chair with comfort by adjusting the footrest22 length so that the footplate 54 is located an appropriate distancefrom the front edge 40 of seat base 12 to allow them to comfortably resttheir feet on footplate 54 when seated on seat base 12.

The seat base attachment portion 56 of the first footrest portion 44 ispivotably attached to the footrest attachment portion 52 of seat base12. Thus, footrest 22 can be pivoted about front edge 40 of seat base 12to allow a user to pivot the footrest 22 out of the way when sittingdown or getting up from the chair.

In the ‘rest’ position, the footrest 22 will hang approximatelyvertically under the influence of gravity. When sitting down, a userwill typically position their legs slightly under the seat base 12. Asthey move their legs into this position, the back of their lower legswill apply force to the footrest 22 to pivot it away from the verticaland slightly under the seat base 12. As the user relaxes in the chair,and moves their lower leg forwards, the footrest 22 will return undergravity to the vertical ‘rest’ position and the user may then placetheir feet on the footplate 54. This movement of the footrest 22 awayfrom the vertical and under the seat base 12 is particularly useful whena user has their feet on the ground and is attempting to slide thechair, for example, under a desk or table. The footrest 22 will thenswing away from the vertical under the influence of the user's legs,thereby not interfering with the user's intention whilst sliding thechair in a forward direction.

Alternatively, the pivot design could be modified to bias the footrestin the ‘rest’ position such that the footrest 22 will naturally sitvertically. However, due to the pivot geometry, if the chair is pushedbackwards or forwards, the footrest 22 will swing under the influence ofcontact with the user's lower legs. However, if a downward force isapplied to the footplate 54 by a user sitting in the chair, movement ofthe footrest 22 away from the vertical will be move difficult i.e. thegreater the weight applied to the footplate 54, the harder it will be toswing the footrest 22 backwards and forwards. This ensures that, whensitting in the chair, the footrest 22 is less likely to swing away fromthe vertical when a user is resting their weight on the footplate 54through application of force through their feet.

It is to be appreciated that the latch design for both the backrest andfootrest adjustment mechanisms is such that when load is applied it isnot the pivots that are loaded. Instead, it is the outside of the catchthat are loaded such that the latch is pushed in against the recess inwhich it is received. This avoids the situation where the pivots couldshear under the weight of a user.

A seat back adjustment mechanism is located on each side of the chair inthe described embodiment. However, a single footrest adjustmentmechanism is provided, thereby providing the advantage of single-handedadjustment of the distance of the footplate 54 from the seat base 12.

A centrally located pivot point for the footrest relative to the seatbase is provided in the described embodiment, rather than a pivot pointbeing provided at each side of the front edge of the seat base. Thecentrally located pivot point is out of reach of a user sitting on thechair. Whereas, if the pivot point was located at each side of the frontedge of the seat base, there is a potential risk of the user's fingersbeing trapped when swinging the footrest if their hands were restingtowards the front edge of the seat base 12.

1. An adjustable chair comprising: a. a seat base defining a seating surface portion for receiving a user thereon in use, the seat base comprising an integral seat back engagement portion for engaging with a portion of a seat back, a seat front portion opposing the seat back engagement portion, a first seat side portion and a second seat side portion opposing the first seat side portion, each of the first and second seat side portions located between the seat back engagement portion and the seat front portion and extending substantially transverse to the seat surface portion; and b. a seat back having a seat base engagement portion dimensioned to slidably engage with the seat back engagement portion to form a seat back adjustment mechanism, wherein the seat back adjustment mechanism is located adjacent at least one of the first and second seat side portions and wherein the seat back adjustment mechanism is movable between a first locked configuration in which the seat back and seat base are fixed relative to one another and the seating surface portion has a fixed surface area, and a second released configuration in which the seat back is slidable relative to the seat base to vary the surface area of the seating surface portion.
 2. An adjustable chair as claimed in claim 1, wherein the seat back adjustment mechanism comprises: a. a first engagement portion for engagement with a latch; and b. a latch pivotable about a pivot point, the latch comprising a second engagement portion for engagement with the first engagement portion, wherein the latch is pivotable between the first locked configuration in which the first and second engagement portions are in rigid engagement with one another and the seat back and seat base are fixed relative to one another, and the second released configuration in which the first and second engagement portions are in slidable engagement with one another and the seat back is slidable relative to the seat base.
 3. An adjustable chair as claimed in claim 2, wherein the first engagement portion comprises a plurality of recesses, each recess being dimensioned to receive at least a portion of the second engagement portion therein.
 4. An adjustable chair as claimed in claim 3, wherein the latch is biased towards the first engagement portion.
 5. An adjustable chair as claimed in claim 4, wherein the latch is biased towards the first engagement portion under force from a coil spring engaged with the latch and arranged between the latch pivot point and the second engagement portion.
 6. An adjustable chair as claimed in claim 5, wherein the latch is pivotable between the first locked configuration and the second released configuration on application of force to a portion of the latch located distal to the second engagement portion.
 7. An adjustable chair as claimed in claim 2, wherein the seat base engagement portion comprises the first engagement portion and the seat back engagement portion comprises the latch.
 8. An adjustable chair as claimed in claim 1, further comprising a footrest extending away from the seat base, the footrest comprising: a. a first footrest portion extending away from the seat base, the first footrest portion comprising a footrest engagement portion for engagement with a second footrest portion; and b. a second footrest portion comprising a footplate for receiving the feet of a user in use, the second footrest portion having a first footrest engagement portion dimensioned to slidably engage with the footrest engagement portion to form a footrest adjustment mechanism, and the footplate being arranged distal to the first footrest engagement portion, wherein the footrest adjustment mechanism is moveable between a footrest locked configuration in which the first and second footrest portions are in fixed engagement with one another and the footplate is at a fixed distance from the seat base, and a footrest released configuration in which the first and second footrest portions are slidable relative to one another to adjust the distance between the footplate and the seat base.
 9. An adjustable chair as claimed in claim 8, wherein the footrest adjustment mechanism comprises: a. a first engagement portion for engagement with a latch; and b. a latch pivotable above a fixed pivot point, the latch comprising a second engagement portion for engagement with the first engagement portion, wherein the latch is pivotable between the footrest locked configuration and the footrest released configuration.
 10. An adjustable chair as claimed in claim 9, wherein the footrest adjustment mechanism first engagement portion comprises a plurality of recesses, each recess being dimensioned to receive at least a portion of the footrest adjustment mechanism second engagement portion.
 11. An adjustable chair as claimed in claim 10, wherein the footrest adjustment mechanism latch is biased towards the plurality of recesses of the footrest adjustment mechanism.
 12. An adjustable chair as claimed in claim 11, wherein the footrest adjustment mechanism latch is biased towards the plurality of recesses of the footrest adjustment mechanism under force from a second coil spring engaged with said latch and arranged between the pivot point of said latch and the footrest adjustment mechanism latch recess engagement portion.
 13. An adjustable chair as claimed in claim 12, wherein the footrest adjustment mechanism latch is pivotable between the footrest locked configuration and the footrest released configuration on application of force to a portion of the said latch located distal to the latch recess engagement portion.
 14. An adjustable chair as claimed in claim 9, wherein the first footrest portion comprises the first engagement portion and the second footrest portion comprises the footrest adjustment mechanism latch.
 15. An adjustable chair as claimed in claim 8, wherein the first footrest portion is pivotally engaged with the seat base.
 16. An adjustable chair as claimed in claim 15, wherein the footrest is pivotable from the vertical position to a position beneath the seat base.
 17. An adjustable chair as claimed in claim 16, wherein the footrest is pivotable from the vertical position in a direction away from the seat base.
 18. An adjustable chair as claimed in claim 15, wherein the seat base defines a first plane and the footrest pivots in a second plane, wherein the first and second planes are transverse to one another. 